From: elen.song@atmel•com (Elen Song)
To: linux-arm-kernel@lists•infradead.org
Subject: [question] some question about the residue
Date: Tue, 27 Nov 2012 10:39:46 +0800 [thread overview]
Message-ID: <50B427F2.30204@atmel.com> (raw)
In-Reply-To: <20121126104027.GD19440@n2100.arm.linux.org.uk>
On 2012-11-26 18:40, Russell King - ARM Linux wrote:
> On Mon, Nov 26, 2012 at 06:37:28PM +0800, Elen Song wrote:
>> So residue actually means current active descriptor remain, it should
> No, not the current active descriptor - the transfer identified by the
> cookie, and only that transfer.
Hi Russell King:
Thank you for your explanations.
Here I got an example, perhaps you can help me figure out if it is
correct.
//allocate a cyclic transfer with 2 descriptors, a cookie identify
current transfer.
desc = dmaengine_prep_dma_cyclic(chan,
sg_dma_address,
sg_dma_len,
sg_dma_len/2,
DMA_DEV_TO_MEM);
cookie= dmaengine_submit(desc);
//if transfer in progress, state.residue is current transfer
remain(sg_dma_len remain), not current descriptor remain(sg_dma_len/2
remain).
device_tx_status(chan,cookie, &state);
Is it right?
Best Regards
next prev parent reply other threads:[~2012-11-27 2:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-26 6:43 [question] some question about the residue Elen Song
2012-11-26 6:49 ` Vinod Koul
2012-11-26 7:35 ` Elen Song
2012-11-26 10:22 ` Russell King - ARM Linux
2012-11-26 10:37 ` Elen Song
2012-11-26 10:40 ` Russell King - ARM Linux
2012-11-27 2:39 ` Elen Song [this message]
2012-11-26 10:19 ` Russell King - ARM Linux
-- strict thread matches above, loose matches on Subject: below --
2012-11-26 3:19 Elen Song
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